Known washing machines include a suspension system for suspending a wash tub, a basket, a motor, and a transmission, and clothes and water loads, within a cabinet, and for damping movement of the wash tub and basket. Known suspension systems include an upper frame and a lower frame. The upper frame is secured to, and supported by, the cabinet. The lower frame is coupled to the upper frame, and the lower frame is movable relative to the upper frame. The wash tub, basket, motor and transmission are coupled to the lower frame.
In one known configuration, suspension rods extend from the lower frame to the upper frame. The suspension rods are secured, at first ends, to cylinder and piston assemblies mounted to the lower frame so that the lower frame can move relative to the suspension rods. Allowing the lower frame to move relative to the suspension rods facilitates damping wash tub and basket movement.
The suspension rods are secured, at second ends, to the upper frame. In one known embodiment, plastic ball joints having longitudinal slots are snap fit to respective rods. The ball joints are positioned on respective seats in the upper frame. The tight fit between the ball joints and the suspension rods prevents the rods from moving longitudinally relative to the ball joints.
With the above described configuration, the ball joint slot dimensions typically must be within relatively tight tolerances so that the ball joint fits tightly with the suspension rod to avoid early failure of the rod. For example, if a snap fit is too loose, a suspension rod could move relative to a ball joint, and such movement can result in early failure of the rod. The fit between the rod and ball joint cannot be too tight, however, because such a tight fit can result in assembly difficulties. Particularly, if the fit between the ball joint and the rod is too tight, it may be very difficult, if not impossible, to snap the ball joint onto the suspension rod.
The relatively tight tolerance requirements of the above described ball joint also adds cost to washing machine assembly. Specifically, any ball joint that does not satisfy the tolerance requirements is not used. Further, if the ball joint is molded, the mold used in the molding process must be precisely machined to satisfy the tolerance requirements. Such machining often requires a skilled and experienced machine operator. In addition, over time, the mold can wear and the relatively tight tolerance requirements for ball joints molded using the mold may not be satisfied. Under such circumstances, the ball joint may fit more loosely than desired with the suspension rod. As explained above, such a loose fit can result in early failure of the suspension rod.
In addition to the assembly difficulties described above, the ball joint also is difficult to disassemble from the suspension rod. Particularly, during servicing, it may be necessary to remove the ball joints from the suspension rods in order to remove the wash tub or other components from within the cabinet. Due to the tight fit between the ball joint and rod, however, it may be extremely difficult to remove the ball joint from the rod.
It would be desirable to provide an upper ball joint assembly for a washing machine suspension assembly that is relative simple and easy to assemble and disassemble. It also would be desirable to provide such an upper ball joint assembly that does not require relatively tight manufacturing tolerances.